Liquids may be treated or processed by the addition of oxidizers for performing a disinfection process. One example is water treatment. Oxidizer materials may be added to water in order to destroy or kill organic and biological materials in the water. Oxidizer materials for use in water treatment may include but are not limited to chlorine, chlorine dioxide, monochloramine, hypobromous acid, hydrogen peroxide, potassium permanganate, and oxygen/ozone.
A typical stage in a water treatment process comprises adding chlorine (or any other suitable oxidizer), with the added chlorine reacting with dissolved contaminants and disinfecting the water. For waste water treatment processes or other treatment involving discharge into natural water bodies (for example, ballast water treatment), this is followed by a de-chlorination stage to remove excess or remaining oxidant. The dechlorination process may comprise adding reducing agents such as SO2, HSO3−, and SO32− into chlorinated water to consume any residual chlorine/oxidizer. The final stage comprises measuring the oxidant residual level in the water to ensure that oxidizer levels are within desired bounds or permitted amounts.
Typically, government regulations specify a maximum or acceptable level of oxidizing materials that may remain in treated water, such as drinking water or wastewater final effluent. Consequently, municipal water treatment processes may require testing in order to ensure that oxidizing materials have been sufficiently removed and to ensure regulatory compliance.
Chlorine measurement in water is often achieved through batch processing, with the measuring comprising obtaining a water or liquid sample, adding a chemical reactant to the sample, waiting a known time period for the chemical reactant to react with available chlorine, and measuring the amount of remaining chlorine.